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Below shows two types of CM choke winding:

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Is there a difference betwween two in applications? They are both used in literature, yet I havent seen a single sentence abou the digg

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    \$\begingroup\$ Just looking at them: the one on the left will have less parasitic inductance (i.e., differential mode), while the one on the right will have less interwinding capacitance. \$\endgroup\$ – Evan Dec 7 '18 at 18:56
  • \$\begingroup\$ Does that mean the one on the riight will attenuate differential mode signal moe?. \$\endgroup\$ – floppy380 Dec 7 '18 at 19:24
  • \$\begingroup\$ This topic is crazy there is no good explanation on net \$\endgroup\$ – floppy380 Dec 7 '18 at 19:24
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The second type can be made with a large spacing between the wires so that it's suitable for mains differential voltage. The one shown below has a 1500VAC test voltage. It is suited for high voltage power filtering.

enter image description here

The first type can be manufactured with controlled differential impedance, so it is suited to high frequency signal filtering.

enter image description here

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  • \$\begingroup\$ If the choke is used right at the output of a DC power supply to supress 1Meg to 5MegHz CM interference,do both type of winding work? \$\endgroup\$ – floppy380 Dec 7 '18 at 19:22
  • \$\begingroup\$ They'll both work, given proper core material for the purpose, The left hand one might allow a somewhat smaller core for the same differential current. \$\endgroup\$ – Spehro Pefhany Dec 7 '18 at 19:45
  • \$\begingroup\$ Thank you Im very new to the subject please have a look at my other question if you have time: electronics.stackexchange.com/questions/411067/… \$\endgroup\$ – floppy380 Dec 7 '18 at 23:52
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The choke on the left maintains a somewhat constant spacing between wires thus maintaining a similar characteristic impedance and thus is better suited for RF applications than the choke on the right which makes no effort to maintain a constant characteristic impedance throughout the choking function. For RF applications, a constant stable characteristic impedance is a desirable feature for chokes.

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